Rickettsia slovaca and R. raoultii in Tick-borne Rickettsioses

Tick-borne lymphadenopathy (TIBOLA), also called Dermacentor-borne necrosis erythema and lymphadenopathy (DEBONEL), is defined as the association of a tick bite, an inoculation eschar on the scalp, and cervical adenopathies. We identified the etiologic agent for 65% of 86 patients with TIBOLA/DEBONEL as either Rickettsia slovaca (49/86, 57%) or R. raoultii (7/86, 8%)

Rapid Detection of Carbapenem Resistance in Acinetobacter baumannii Using Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry

Rapid detection of carbapenem-resistant Acinetobacter baumannii strains is critical and will benefit patient care by optimizing antibiotic therapies and preventing outbreaks. Herein we describe the development and successful application of a mass spectrometry profile generated by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) that utilized the imipenem antibiotic for the detection of carbapenem resistance in a large series of A. baumannii clinical isolates from France and Algeria. A total of 106 A. baumannii strains including 63 well-characterized carbapenemase-producing and 43 non-carbapenemase-producing strains, as well as 43 control strains (7 carbapenem-resistant and 36 carbapenem-sensitive strains) were studied. After an incubation of bacteria with imipenem for up to 4 h, the mixture was centrifuged and the supernatant analyzed by MALDI-TOF MS. The presence and absence of peaks representing imipenem and its natural metabolite was analyzed. The result was interpreted as positive for carbapenemase production if the specific peak for imipenem at 300.0 m/z disappeared during the incubation time and if the peak of the natural metabolite at 254.0 m/z increased as measured by the area under the curves leading to a ratio between the peak for imipenem and its metabolite being <0.5. This assay, which was applied to the large series of A. baumannii clinical isolates, showed a sensitivity of 100.0% and a specificity of 100.0%. Our study is the first to demonstrate that this quick and simple assay can be used as a routine tool as a point-of-care method for the identification of A. baumannii carbapenemase-producers in an effort to prevent outbreaks and the spread of uncontrollable superbugs

Mitochondrial physiology

As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery

Mitochondrial physiology

As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery

Polymérisation de l'isoprène par catalyse terres rares en présence de dérivés inorganiques (accès à des nouveaux élastomères composites)

Deux systèmes catalytiques hétérogènes, l un à base de trisphénate de néodyme (Nd(O(C6H3tBu2)3 associé au MAO supporté sur kaolin, et l autre constitué d un metal-organic framework (MOF) à base de néodyme activé par des aluminoxanes (MAO et MMAO), ont été évalués pour la polymérisation par coordination contrôlée de l isoprène, de type polymérisation in situ , dans le but de préparer des élastomères composites. Le trisphénate de néodyme, étudié de façon préliminaire comme pré-catalyseur dans des conditions conventionnelles, conduit à des catalyseurs single-site en association avec des co-catalyseurs aluminoxanes, alors que la formation de polymères hautement 1,4-cis stéréoréguliers est obtenue par activation avec AlEt2Cl. En conditions de polymérisation hétérogène, chacun des systèmes catalytiques préparés se révèlent actifs, et produisent des polyisoprènes hautement 1,4-cis. La stéréosélectivité est clairement reliée à la porosité du pré-catalyseur dans le cas des MOF. Les matériaux polymériques montrent la présence de résidus cristallins de type MOF ou kaolin, ce qui a permis de les classer comme matériaux microcomposites. La présence de ces résidus inorganiques, dispersés dans les matrices polymériques, induisent notamment une modification des températures de transition vitreuse. Ces microcomposites sont les premiers exemples de polyisoprènes composites obtenus par des MOFs à base de néodyme, et par polymérisation in situ par des argiles supportées en association avec des post-métallocènes de néodyme.Two types of heterogeneous catalytic systems, based on the neodymium trisphenoxide (Nd(O(C6H3tBu2)3, associated to a MAO supported kaolin, and on a neodymium metal-organic framework based (MOF), activated by aluminoxanes, were studied by controlled coordination polymerisation of isoprene, with the aim of preparing composite elastomers. The neodymium trisphenoxide, studied in a preliminary way as pre catalyst in conventional conditions, affords single site catalysts in association with aluminoxanes co catalysts. Polymers highly 1,4-cis regular are obtained with additional activation with AlEt2Cl. In heterogeneous polymerisation conditions, each of the catalytic systems were found active, and giving rise to highly 1,4-cis regular polyisoprenes. The stereoselectivity is clearly related to the pre catalyst porosity (in the MOF case). The polymeric materials showed the presence of crystalline residues of MOF type or kaolin, which allowed to classify them as microcomposites. The presence of inorganic residues, dispersed into the polymeric matrix, induces a modification of glass transition temperature. These microcomposites are the first example of polyisoprene based composites obtained with neodymium MOFs, and by in situ polymerisation by supported clays in association with neodymium post-metallocenesLILLE1-Bib. Electronique (590099901) / SudocSudocFranceF

Etude de p8/TTD-A, une sous-unité de TFIIH impliquée dans la Trichothiodystrophie de type A (Structure et interactions avec ses partenaires)

Le facteur TFIIH est un complexe multi-protéique composé de 10 sous-unités, impliqué dans l initiation de la transcription ainsi que dans la réparation de l ADN par excision resynthèse. Des mutations dans les gènes codant pour trois de ses sous-unités sont à l origine de trois maladies héréditaires caractérisées par des défauts de réparation et/ou transcription. Je me suis focalisé sur la sous-unité p8, dont une absence ou un dysfonctionnement sont à l'origine de la trichothiodystrophie de groupe A. J ai déterminé la structure de p8 par RMN et étudié avec diverses approches biophysiques des complexes entre p8 et p52, son partenaire dans le complexe TFIIH. L interprétation de ces données, à la lumière de la structure cristalline du complexe p8-p52 de levure, fourni une explication moléculaire des effets déstabilisateurs des mutations observées chez les malades. J ai également participé à la conception d une nouvelle méthode d enregistrement de données de relaxation par RMN, permettant l accès au temps de corrélation de rotation d une protéine en solution avec un gain de temps d un facteur quatre par rapport aux enregistrements classiques.TFIIH, a multi-subunit complex composed of 10 subunits, is important for transcription initiation and for DNA nucleotide excision repair. Mutations in the genes coding for three TFIIH subunits cause hereditary diseases characterized by defects in repair and/or transcription. I focused on p8, a subunit whose absence or dysfunction cause type A trichothiodystrophy. I determined the structure of p8 by NMR and studied, with diverse biophysical approaches, complexes between p8 and p52, its partner within TFIIH. Interpretation of these data, in the light of yeast crystal structure of p8-p52 complex, provides a molecular explanation of the destabilizing effects caused by the mutations observed in patients. I also participated in the conception of a novel method for recording NMR relaxation data, allowing the rotational correlation time of a protein to be determined in a time four times shorter than classical experiments.STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

Polymères nanocomposites par polymérisation au sein d'un renfort minéral modifié lanthanide

Communication oral

Lanthanide metal-organic frameworks as ziegler–natta catalysts for the selective polymerization of isoprene

The unprecedented ability of neodymium-based metal organic frameworks (MOFs) aspolymerisation pre-catalysts towards isoprene is reported. Combined with methylaluminoxane(MAO) or modified MAO (MMAO), they afford mainly cis-selective polyisoprene, up to90.7%. Both the activity and the selectivity are tentatively ascribed to the intrinsic microstructureof the starting materials. Compared to conventional carboxylates, MOFs associatedto an Al co-catalyst are less active but the selectivity is found to be higher, and itmay be modified by controlling the access to the pores, which would be favored at highertemperatures. Some residual crystallineMOF remains disseminated within thepolymer matrix, as shown by X-raydiffraction and X-ray absorption spectroscopystudies

Elastomers Nanocomposites by stereospecific in-situ polymerization within a metal-organic framework

Communication par affich

In vitro studies into establishing therapeutic bioequivalence of complex topical products: Weight of evidence

Over the past decade, topically applied drug products have experienced extraordinary price increases, due to the shortage of multisource generic drug products. This occurrence is mainly related to the underlying challenges evolved in topical bioequivalence documentation. Although there has been continuing regulatory efforts to present surrogate in vitro methods to clinical endpoint studies, there is still a continued need for cost- and time-efficient alternatives that account for product specificities. Hence, this work intended to expose bioequivalence assessment issues for complex topical formulations, and more specifically those related with product efficacy guidance. As a model drug and product, a bifonazole 10 mg/g cream formulation was selected and two different batches of the commercially available Reference Product (RP) were used: RP1 that displayed lower viscosity and RP4 which presented high, but not the highest, viscosity. In vitro human skin permeation testing (IVPT) was carried out and the results were evaluated by means of the traditional bioequivalence assessment approach proposed by the EMA, as well as by the Scaled Average Bioequivalence assessment approach proposed by the FDA. Based on previous experience, there was an expectation of a high level of variability in the results, thus alternative methods to evaluate local drug skin availability were developed. More specifically, an infected skin disease model, where ex vivo human skin was infected and ATP levels were used as a biological marker for monitoring antifungal activity after product application. The results showed that permeation equivalence could not be supported between the different RP batches. In contrast, this statistical difference between the formulation batches was not indicated in the disease model. Nevertheless, in pivotal IVPT studies, the lowest permeant formulation (RP4) evidenced a higher antifungal in vitro activity as reported by the lower levels of ATP. A critical appraisal of the results is likewise presented, focusing on an outlook of the real applicability of the regulatory guidances on this subject